Spool valve

ABSTRACT

A four-way spool valve in which the spool assembly is hollow and consists of two relatively telescoped spool members. The hollow interiors of the spool members communicate exclusively with transverse openings formed in the spool members and the spool members are movable relative to each other and to the valve casing so that they cooperate with the casing to define four valve positions.

United States Patent S T N M MA .IP a cT A e ..T S e D E W N U m h. w.MM r Mm A m HA m n e V rm U 7 211 AppLNo 882,223 221 Filed 137/625.63X137/625 68 X 137/596.16X

Dec. 4, 1969 [45] Patented June 15, 1971 [73] Assignee Olmsted ProductsCo.

Ann Arbor, Mich.

ABSTRACT: A four-way spool valve in which the spool assembly is hollowand consists of two relatively telescoped spool members. The hollowinteriors of the communicate exclusively with transverse o the spoolmembers and the spool members [54] SPOOL VALVE 9 Claims, 4 Drawing Figs.

spool members penings formed in are movable relative to each other andto the valve casin cooperate with the casing to define four valve 0 1 l1 k 6 1 F [51] lnt.C1.......,............. [50] FieldofSearch....

g so that they positions.

PATENTEU JUN] 5197:

SHEET 1 OF 2 INV PETER B. OLMST ATTORNEYS PATENTEU JUHI 5 I971 SHEET 2OF 2 FIG. 4

INVENTOR PETER B. OLMSTED ATTORNEYS SPOOL VALVE The principal object ofthis invention is to provide an improved four position spool valve.

The spool valve of this invention is particularly adapted for use with afluid actuated cylinder assembly in which the piston rod is advanced toperform work, retracted in preparation for the next work cycle, and heldat rest between cycles. At the start of a work cycle, rapid advance ofthe piston rod is desirable for efficiency purposes. This isaccomplished in the spool valve of this invention by providing a"regeneration" position of the spool assembly in which flow of fluidfrom the rod end of the cylinder joins the flow from the pump feed fluidto the head end of the cylinder. When the resistance to motion of thepiston rod increases to the point where rapid advance is no longerpossible, the spool assembly is moved to a work" position in which therod end of the cylinder connects to tank. These desirable valvepositions are accomplished in the fourway valve of this invention by theprovision of a hollow two member spool assembly in which the spoolmembers are relatively movable between four positions.

Further objects, features and advantages of this invention will becomeapparent from a consideration of the following description, the appendedclaims, and the accompanying drawing in which:

FIG. l is a longitudinal sectional view of the spool valve of thisinvention, illustrating diagrammatically the assembly of the spool valvewith a fluid actuated cylinder assembly and showing the valve componentsin the "rest" position of the valve;

FIG. 2 is a longitudinal sectional view of the spool valve of thisinvention, illustrated similarly to FIG. 1, showing the spool assemblymoved to a position in which the valve com ponents define the workposition of the valve; and

FIGS. 3 and 4 are longitudinal sectional views similar to FIGS. 1 and 2showing the valve components in positions corresponding to return" andregeneration valve positions.

With reference to the drawing, the improved spool valve of thisinvention, indicated generally at 10, is illustrated in FIG. 1 connectedto a fluid operated cylinder assembly 12, a pump 14, and a tank 16 whichsupplies fluid to the pump 14. The pump 14 and the tank 16 are showndiagrammatically, since they are conventional, it being understood thatthe pump 14 communicates in the usual way with tank 16. As shown in FIG.I, the valve consists of a casing 18 in which a longitudinal bore 20 isformed, the bore having an axis 22. Annular lands 24 are formed in thecasing 18 so that they constitute a portion of the bore 20 and cooperateto form four axially spaced chambers 26, 28, 30 and 32 in the casing 18.A tank port 34 formed in the casing 18 connects the chamber 26 to apassage 36 that communicates with the tank 16. A first work port 38 inthe casing 18 communicates with the chamber 28 and with a conduit 40which is in turn connected to the blind end 42 of the cylinder 44 in thecylinder assembly 12. A pump port 46 in the casing 18 communicates withthe chamber 30 and with a conduit 48 connected to the pump 14. A secondwork port 50 communicates with the valve chamber 32 and with a conduit52 which connects to the rod end 45 of the cylinder 44.

A spool assembly 54 is slidably supported in the bore 20 in substantialsealing engagement with the lands 24 at a position axially aligned withthe bore axis 22. The spool assembly 54 consists of a pair of spoolmembers 56 and 57 which are movable toward each other to the limitpositions shown in FIG. 1. Pilot fluid chambers 58 and 60 are formed atthe ends of the spool assembly 54 when the spool assembly is in theposition shown in FIG. 1. The spool members 56 and 57 are movable apartto the limit positions shown in FIG. 4 in which opposite ends of thespool assembly 54 engage the casing end walls 62 and 64.

The first spool member 56 consists of a body 66 of a diametercorresponding substantially to the diameter of the lands 24 and having areduced diameter tubular extension 68. The tubular extension 68 containsan internal cavity 70 which extends into the body 66 and is connected toa transverse passage 72 in a reduced diameter portion 74 of the body 66.It can be seen from FIGS. 14 that in all four positions of the spoolassembly 54, the opening 72 communicates with the tank port 34. At oneend, the body 66 is formed with an enlarged head 76 which is engageablewith an internal shoulder 78 in the casing 18 to limit movement of thespool member 56 in response to a supply of fluid under pressure to thepilot fluid chamber 58.

The second spool member 57 consists of a body 80 provided with aninternal chamber 82 into which the first spool member extension 68 istelescoped. As shown in FIGS. 1 and 4, the spool member extension 68 istelescopable substantially all the way into the chamber 82 (FIG. 1) toan inner position and is movable to an outer position (FIG. 4) in whichthe extension 68 is substantially withdrawn from the chamber 82. Asshown in FIG. 1, when the extension 68 is in its inner position, anexternal shoulder 88 on the spool member 56 is spaced from the inner endsurface 90 of the spool member 57. As a result, fluid under pressure inthe valve chamber 30 applies oppositely directed forces to the spoolmembers 56 and 57 tending to urge them apart. Intermediate its ends, thespool member 57 has a reduced diameter portion 92 which cooperates withthe casing 18 to form an annular chamber 94 therebetween. Inclinedpassages 96 in the body 80 provide for continuous communication of thechamber 94 and the internal chamber 82 for a purpose to appearpresently. An external shoulder 93 on the spool member 57 is engageablewith a casing stop shoulder 95 to limit movement of member 57 towardmember 56.

In the operation of the spool valve 10, assume that it is desired tohave the cylinder assembly 12 at rest. The rest" condition of thecylinder assembly 12 exists when both the blind end 42 and the rod end45 of the cylinder 44 are connected to tank. In the valve 10, pilotfluid pressure is applied to both the chambers 58 and 60 so as to movethe spool assembly 54 to its telescoped position shown in FIG. I. Inthis position of the spool assembly 54, it positively blocks the pumpchamber 30 so that it does not communicate with the chambers 28 and 32on either side thereof. The chamber 28 communicates around the spoolassembly 54 with the tank chamber 26 and the chamber 32 communicatesthrough the spool passages 96 and the spool opening 72 with the tankchamber 26.

Now, assume that it is desired to rapidly advance the piston 97 in thecylinder assembly 12. Both of the chambers 58 and 60 are vented so thatpressure from the pump chamber 30 acting on the surfaces 88 and 90 movesthe spool members 56 and 57 rapidly apart ad into engagement with thecasing end walls 62 and 64, as shown in FIG. 4-. In this position of thespool assembly 54, it is seen that the pump chamber 30 communicatesdirectly with the work chambers 28 and 32 so that as the. piston 97 isadvanced, the fluid from the rod end 45 of the cylinder 44 joins theflow of fluid from chamber 30 to chamber 28 to feed the blind end 42 ofthe cylinder 44 through the work port 38. Because the fluid from the rodend of the cylinder 44 is being used to supplement the fluid flowingfrom the pump 14 to the work port 38, this position of the spoolassembly 54 shown in FIG. 4 is referred to as the "regenerationposition.

When the resistance to motion of the piston 97 increases to the pointwhere rapid advance is no longer possible, pilot pressure fluid is againsupplied to chamber 60 while continuing to vent pilot chamber 58. Thisprovides for movement of the spool member 57 to the position shown inFIG. 2 in which the tubular extension 68 is telescoped further into thechamber 82. In this position of the spool member 57, it blockscommunication between the pump chamber 30 and the work chamber 32 andprovides for communication of the work chamber 32 with the internalspool chamber 82 through the passages 96. Thus, the chamber 32 connectsto tank 16 to in turn connect the rod end 45 of the cylinder 12 to tank.Since the position of the spool member 56 has not changed, fluid underpressure continues to be supplied to the blind end 42 of the cylinder44.

When the work to be accomplished with the cylinder assembly 12 has beencompleted, it is desired to retract the piston 97 so that the abovedescribed work cycle can be repeated. The pilot chamber 60 is vented andfluid under pressure is supplied to the chamber 58 so as to move thespool assembly 54 to the position shown in H0. 3 in which the spoolmembers 56 and 57 are in the same relative positions that they were inin the FIG. 2 "work position. the return" position of the spool valveshown in FIG. 3, the work port 38 communicates with the tank port 34,the work port 50 communicates with the pump port 46 and communication ofany of the valve ports through the hollow interior of the spool assembly54 is precluded because of the isolated position of the chamber 94. Oncethe piston 97 has been returned, the above described cycle can berepeated by again supplying fluid under pressure to the pilot chamber 60so as to return the spool assembly 54 to its "rest" position shown inFIG. 1.

From the above description it is seen that this invention provides aspool valve 10 in which four-way operation of the spool valve is readilyaccomplished by virtue of the hollow two piece construction of the spoolassembly 54. This enables movement of the spool assembly to the fourpositions illustrated in FIGS. l4, inclusive, so as to move the cylinderassembly l2 efficiently through a work cycle.

What! claim is:

1. In a spool valve having a casing provided with a plurality of ports,a spool assembly having a longitudinal axis, said spool assemblycomprising a pair of members one of which has a tubular portionextending along said axis, means forming an opening in said one membercommunicating with said tubular portion, the other one of said spoolmembers having a tubular portion telescopable over said first tubularportion, means forming an opening in said other one of said spoolmembers communicating with said tubular portion thereof, the interiorsof said tubular portions communicating exclusively with said openings,said members being mounted in said casing for relative sliding movementalong said axis to different positions relative to said ports in whichat least one of said openings communicates with at least one of saidports.

2. A spool valve according to claim 1 wherein said spool members areprovided with facing surfaces arranged in a spaced relation in all movedpositions of said spool members.

3. A spool valve according to claim 1 wherein said casing cooperateswith said spool members in the telescoped positions of said members todefine a pair of pilot fluid chambers in said casing at opposite ends ofsaid spool assembly.

4. A spool valve according to claim 1 wherein said plurality of portsconsists of a pump port, a tank port and two work ports, said spoolmembers being movable in directions away from each other to positions inwhich communication of said pump port with both said work ports isprovided and communication between said tank port and all other ports isblocked.

5. A spool valve according to claim 3 wherein said plurality of portsincludes a pump port, a tank port and two work ports, said spoolassembly in relatively telescoped positions of said spool membersproviding for communication of said tank port with said work ports andblocking communication of said pump port with all other ports.

6. A spool valve according to claim 5 wherein each of said spool membersis movable in a direction away from the other spool member to providefor communication of said pump port with one of said work ports.

7. A spool valve comprising a casing having a bore, said casing beingprovided with a pump port, a tank port and two work ports whichcommunicate with said bore, a spool assembly slidably mounted in saidbore for movement axially thereof, said assembly comprising a firstspool member having a body portion and a hollow extension, said bodyportion being of a diameter to slidably support said first spool memberin said bore a second spool member telesco ed over said hollow extensionand movable axially thereof etween limit positions,

said second spool member having an internal chamber communicating withthe interior of said hollow extension, said spool members being providedwith passages which communicate with said chamber and the interior ofsaid hollow extension, said chamber and the interior of said extensioncommunicating exclusively with said passages, said spool members beingmounted in said bore for movement toward each other to one of said limitpositions in which pilot fluid chambers are formed in said bore atopposite ends of said spool assembly, each of said spool members beingmovable in a direction away from the other spool member to a stopposition in said casing, said spool members being relatively movable insaid casing to different positions relative to said ports in which atleast one of said passages communicates with at least one of said ports.

8. A spool valve according to claim 7 further including axially spacedlands in said bore supporting said spool assembly and defining aplurality of chambers spaced axially along said spool assembly, each ofsaid chambers corresponding to and being in continual fluidcommunication with one of said ports.

9. A spool valve according to claim 8 wherein one of said spool memberpassages is in continual communication with said tank port.

1. In a spool valve having a casing provided with a plurality of ports,a spool assembly having a longitudinal axis, said spool assemblycomprising a pair of members one of which has a tubular portionextending along said axis, means forming an opening in said one membercommunicating with said tubular portion, the other one of said spoolmembers having a tubular portion telescopable over said first tubularportion, means forming an opening in said other one of said spoolmembers communicating with said tubular portion thereof, the interiorsof said tubular portions communicating exclusively with said openings,said members being mounted in said casing for relative sliding movementalong said axis to different positions relative to said ports in whichat least one of said openings communicates with at least one of saidports.
 2. A spool valve according to claim 1 wherein said spool membersare provided with facing surfaces arranged in a spaced relation in allmoved positions of said spool members.
 3. A spool valve according toclaim 1 wherein said casing cooperates with said spool members in thetelescoped positions of said members to define a pair of pilot fluidchambers in said cAsing at opposite ends of said spool assembly.
 4. Aspool valve according to claim 1 wherein said plurality of portsconsists of a pump port, a tank port and two work ports, said spoolmembers being movable in directions away from each other to positions inwhich communication of said pump port with both said work ports isprovided and communication between said tank port and all other ports isblocked.
 5. A spool valve according to claim 3 wherein said plurality ofports includes a pump port, a tank port and two work ports, said spoolassembly in relatively telescoped positions of said spool membersproviding for communication of said tank port with said work ports andblocking communication of said pump port with all other ports.
 6. Aspool valve according to claim 5 wherein each of said spool members ismovable in a direction away from the other spool member to provide forcommunication of said pump port with one of said work ports.
 7. A spoolvalve comprising a casing having a bore, said casing being provided witha pump port, a tank port and two work ports which communicate with saidbore, a spool assembly slidably mounted in said bore for movementaxially thereof, said assembly comprising a first spool member having abody portion and a hollow extension, said body portion being of adiameter to slidably support said first spool member in said bore, asecond spool member telescoped over said hollow extension and movableaxially thereof between limit positions, said second spool member havingan internal chamber communicating with the interior of said hollowextension, said spool members being provided with passages whichcommunicate with said chamber and the interior of said hollow extension,said chamber and the interior of said extension communicatingexclusively with said passages, said spool members being mounted in saidbore for movement toward each other to one of said limit positions inwhich pilot fluid chambers are formed in said bore at opposite ends ofsaid spool assembly, each of said spool members being movable in adirection away from the other spool member to a stop position in saidcasing, said spool members being relatively movable in said casing todifferent positions relative to said ports in which at least one of saidpassages communicates with at least one of said ports.
 8. A spool valveaccording to claim 7 further including axially spaced lands in said boresupporting said spool assembly and defining a plurality of chambersspaced axially along said spool assembly, each of said chamberscorresponding to and being in continual fluid communication with one ofsaid ports.
 9. A spool valve according to claim 8 wherein one of saidspool member passages is in continual communication with said tank port.